Slowlint

Implement linting with ESLint slowly on big projects.

WTF

Sometimes you need to add linting to existing projects. And you have to take it lazy to avoid many merge conflicts, failing builds and etc.

That's where Slowlint saves the day.

How it is supposed to work:

1. You add ESLint, ESLint config and .eslintignore to project as usual.
2. You run Slowlint to make a file with all temporary ignores (files which don't pass linting).
3. You add two checks to your CI on every commit:
   • check that all good files still pass linting
   • check that bad files did not become good

This is the least invasive way to ensure that your code will not become worse and will lazily become better.

Step by step

1. ESLint setup

Install ESLint, plugins, set up config, .eslintignore and etc - just as usual.

2. Generate .slowlintignore file

That's same as .eslintignore but with another name. Why bother?

• .slowlintignore only contains files which could be fixed. Files from .eslintignore are not meant to be fixed.
• Any IDE will use .eslintignore and ignore .slowlintignore - just as planned!
• You can use both .eslintignore and .slowlintignore.

Example

slowlint save-ignored --files src test --eslint-path ~/project1/node_modules/eslint

3. Lint

Slowlint can use your existing ESLint package and configuration for linting with both .eslintignore and.slowlintignore files.

That's great for CI!

Example

slowlint lint --files src test --eslint-path ~/project1/node_modules/eslint

4. Check for good files

Slowlint can also check if good files (which pass linting) are included in .slowlintignore file.

Example

slowlint check-good --files src test --eslint-path ~/project1/node_modules/eslint

Installation

// install it locally
npm i slowlint --save-dev

// or install globally
npm i -g slowlint

// or simply run with npx
npx slowlint check-good --files src test --eslint-path ~/project1/node_modules/eslint

Usage

Usage: slowlint <command> [options]

Commands:
  slowlint lint          Lint everything but bad files
  slowlint check-good    Check if good files are listed as bad
  slowlint save-ignored  Make a new list of ignored files

Options:
Options:
  --version         Show version number               [boolean]
  --files           filenames                         [array] [required]
  --eslintPath      eslint path                       [string] [default: "./node_modules/eslint"]
  --ignoreFilePath  path for .slowlintignore file     [string] [default: ".slowlintignore"]
  --noProgress      hide progress bar                 [boolean] [default: false]
  -h, --help        Show help                         [boolean]

Examples:

Lint all files from project in current diirectory using linter and config from project:

slowlint lint --files .

Lint bin and test dirs using linter from some project1:

slowlint lint --files bin test --eslint-path ~/project1/node_modules/eslint